Scientists develop sustainable jet fuel from agricultural waste
03 October 2024
A new method to produce sustainable jet fuel from lignin-based agricultural waste offers a promising solution to reduce the aviation industry's carbon footprint.
Image: WSU
Published in the journal Fuel Processing Technology, Washington State University scientists’ research demonstrated a continuous process that directly converts lignin polymers, one of the chief components of plant cells, into a form of jet fuel that could help improve the performance of sustainably produced aviation fuels.
"Our achievement takes this technology one step closer to real-world use by providing data that lets us better gauge its feasibility for commercial aviation," said lead scientist Bin Yang, Professor in WSU's Department of Biological Systems Engineering.
A class of structural molecules that make plants tough and woody, lignin is derived from corn stover – the stalks, cobs and leaves left after harvest – and other agricultural byproducts.
The team developed a process called "simultaneous depolymerisation and hydrodeoxygenation", which breaks down the lignin polymer and at the same time removes oxygen to create lignin-based jet fuel.
At their Richland facility, the scientists introduced dissolved lignin polymer into a continuous hydrotreating reactor to produce the fuel.
Global consumption of aviation fuel reached an all-time high of nearly 100 billion gallons in 2019, and demand is expected to increase in the coming decades.
Sustainable aviation fuels derived from plant-based biomass could help minimise aviation's carbon footprint, reduce contrails and meet international carbon neutrality goals.
Lignin-based jet fuel could make sustainable fuels cleaner and more easily usable in jet engines. Thanks to their density, efficiency, and seal-swelling characteristics, hydrocarbons catalysed from lignin could effectively replace fossil fuel-derived compounds called aromatics.
Associated with contrails and climate impacts, aromatics remain in use because they enhance fuel density and help swell O-rings in metal-to-metal joints.
This research marked the team's first successful test of a continuous process, which is more feasible for commercial production.
The project also used a less processed, less expensive form of lignin derived from corn stover, dubbed "technical lignin," contrasting similar research using extracted lignin bio-oil.
The team's findings suggest lignin is a promising source of aromatic-replacing cycloalkanes and other useful fuel compounds.
"The aviation enterprise is looking to generate 100 percent renewable aviation fuel," said Josh Heyne, research team member and Co-Director of the WSU-PNNL Bioproducts Institute.
"Lignin-based jet fuel complements existing technologies by, for example, increasing the density of fuel blends."
Offering reduced emissions, lignin-based fuel could ultimately make sustainable aviation fuels fully "drop-in" capable, meaning they can be used with all existing engines, infrastructure and aircraft like existing fossil-derived aviation fuel.
"We're working to create an effective, commercially relevant technology for a complementary blend component that can achieve the 100 percent drop-in goal," Heyne said.
The team is now working to refine their process for better efficiency and reduced costs.